Search Interview Questions |  More than 3000 questions in repository. There are more than 900 unanswered questions. Click here and help us by providing the answer. Have a video suggestion. Click Correct / Improve and please let us know. |
|
|||
|
| |||||||||||
| Core Java - Interview Questions and Answers for 'Optional' - 3 question(s) found - Order By Newest | |||||||||||
 Not frequently asked as it was introduced with Java 8. | |||||||||||
| |||||||||||
| Ans. Optional is a good way to protect application from runtime nullPointerException in case the the absent value has been represented as null. So basically Optional class provides the type checking during compile time and hence will never result in NPE. For ex - List intList.add(Optional.empty()); intList.add(Optional.of(new Employee("abc"))); intList.add(Optional.of(new Employee("xyz"))); intList.add(Optional.of(new Employee("123"))); System.out.println(intList.get(0).getName()); So Now , even when the first list element is empty, this code will never throw an NullPointerException. | |||||||||||
| Help us improve. Please let us know the company, where you were asked this question : | |||||||||||
 Discuss Correct / Improve  java java8 java 8 optional | |||||||||||
 Related Questions | |||||||||||
 Difference between final and effectively final ? Why is effectively final even required ? | |||||||||||
| What is StringJoiner ? | |||||||||||
| Why can't we have diamond problem with interfaces ? | |||||||||||
| Name few "Optional" classes introduced with Java 8 ? | |||||||||||
| What was the driving force to introduce default methods in Interfaces wef from Java 8 ? | |||||||||||
| Is it ok to use optional everywhere just to get over nullpointerexception ? | |||||||||||
| What is concurrent interface ? | |||||||||||
| What are new features introduced with Java 8 ? | |||||||||||
| What is the @FunctionalInterface annotation ? | |||||||||||
| Rarely asked as it was introduced with Java 8. | |||||||||||
| |||||||||||
| Ans. http://www.buggybread.com/2015/01/java-optional-classes-and-interfaces.html | |||||||||||
| Help us improve. Please let us know the company, where you were asked this question : | |||||||||||
| Discuss Correct / Improve java optional java 8 java8 | |||||||||||
| Related Questions | |||||||||||
| Difference between final and effectively final ? Why is effectively final even required ? | |||||||||||
| What is StringJoiner ? | |||||||||||
| Why can't we have diamond problem with interfaces ? | |||||||||||
| What is the use of Optional ? | |||||||||||
| What was the driving force to introduce default methods in Interfaces wef from Java 8 ? | |||||||||||
| Is it ok to use optional everywhere just to get over nullpointerexception ? | |||||||||||
| What is concurrent interface ? | |||||||||||
| What are new features introduced with Java 8 ? | |||||||||||
| What is the @FunctionalInterface annotation ? | |||||||||||
| |||||||||||
| Ans. Optional is to be used for arguments / atrributes which are indeed optional i.e the request should continue even if they aren't provided. It should not be used for mandatory attributes or arguments as we would like application to shout out ( with error message / exception trace ) to signify a problem. | |||||||||||
| Help us improve. Please let us know the company, where you were asked this question : | |||||||||||
Discuss Correct / Improve optional nullpointerexception java8 java 8  Asked in 1 Companies | |||||||||||
| Related Questions | |||||||||||
| What is the use of Optional ? | |||||||||||
| Name few "Optional" classes introduced with Java 8 ? | |||||||||||
| How can we make the constructor variables optional in Typescript ? | |||||||||||
| |||||||||||
Reference
